The present invention provides a GPS based navigation system for use by a swimmer while snorkeling. One would not expect that a snorkeler would need a sophisticated navigation system since all he has to do is raise his head and look around to acquire whatever visual points of reference he might need to find his way around a snorkeling site. Surprisingly, however, providing the snorkeler with a navigation system greatly increases his safety and enjoyment, can have a positive effect on the environment, and can improve the health of the coral reef system as discussed below.
Snorkeling has become increasingly popular among tourists at resorts and parks, and as side excursions on cruises. Most tourists have limited or no snorkeling experience. After donning mask, snorkel and fins, they swim off with only a general idea of where the most interesting sites are. With luck, they might happen upon a good area, but are much more likely to miss most of them entirely. Even with fairly good directions they may still miss their destination due to less than ideal visibility, poor navigation skills, or both.
To solve this problem, a few sites, like the Buck Island Reef National Monument off St. Croix in the US Virgin Islands, have marked underwater trails for snorkelers to follow. However, marking an underwater trail is expensive and difficult to do without taking away the natural beauty of the site. Additional expense and complication arise when maintenance issues develop. And placing permanent markers on a coral reef raises significant environmental issues.
Another problem can arise when a snorkeler ventures into a shallow area where an environmental fragile entity exists, such as a coral bed or delicate sea anemone. In such tight quarters it is easy to contact the entity, causing damage to it and, perhaps, to the snorkeler.
Yet another problem a snorkeler might encounter is that of finding his way back to a given starting point or to some other predetermined exit point. Beaches and coves look remarkably different when viewed from the water rather than from the land. The problem is compounded if the weather suddenly turns inclement. Even if the weather remains mild, waves can obscure details of the shoreline, again making it difficult to find the correct exit point. Even snorkelers who swim from excursion boats can't completely avoid the problem because there are frequently many excursion boats all looking approximately alike at the same site.
Still another problem that a resort snorkeler encounters is that of time management. It is not unusual that he only have so much time to devote to his outing. He may in fact have to meet a tour bus at a particular time or return his rented equipment before the rental shop closes. It is difficult enough to meet that kind of time commitment even if he knows what time it is, yet many resort snorkelers don't have watches that can be used underwater.
Thus snorkelers, and especially inexperienced snorkelers, face a number of issues they aren't aware of when they start. They may not know where they are, where they're going, or how they're going to find the right exit point at the right time. They may stumble into areas that are environmentally fragile or unsafe to swim into. All of these problems become even more daunting if inclement weather suddenly arises, even for experienced snorkelers. And so there exists an unmet need for a navigation system suitable for use by snorkelers.
Navigation systems based on GPS are capable of providing a user with a wide array of information. Even low priced handheld GPS receivers can present latitude and longitude, display a user's position on a graphical map, report speed and heading, compute distance and bearing to preset points, follow predetermined routes or previously stored tracks, estimate time of arrival, and any number of other navigational statistics. A handheld GPS receiver would be ideal for use by a snorkeler if it weren't for the fact the electromagnetic GPS signals cannot penetrate more than a few centimeters into water.
And yet, GPS has been adapted for use underwater. One system that could be used by snorkelers to navigate while swimming is disclosed in U.S. Pat. No. 6,701,252 issued to this applicant, the disclosure of which is incorporated herein by reference. In that system, a GPS signal receiving antenna is located on a float supporting a diver-down flag and connected by wire to a GPS display carried by a scuba diver. By necessity, this system requires that the scuba diver tow the float behind him, but this is not an issue for scuba divers since they frequently have to tow a diver-down flag anyway. But towing a float is an encumbrance for a snorkeler, especially an inexperienced one, because the towline is distracting, occupies one hand, presents a constant drag, and frequently becomes entangled in his arms, legs, and fins.
Still another issue with the above system that makes it less desirable for use by a snorkeler is that the navigational information computed by the system is that for the float, not the scuba diver. In particular, the location and direction of travel of the float is not necessarily that of the scuba diver because the float is at the end of a long towline and is thus slow to respond to a change in direction by the scuba diver. As a result, the scuba diver relies on his own compass for determining his heading instead of the heading reported by the GPS. But a snorkeler does not ordinarily wear a compass and would thus need to keep correcting his direction of motion to compensate for the lag induced by towing a float.
And so there is clearly a need for a navigation system that can be used by a snorkeler not currently met by the state of the art.